Capacitance coupled sensor and substance detecting method using capacitance-coupled sensor

ABSTRACT

To allow a DC voltage to be obtained as an output signal for higher versatility. A sensor unit  400  has three electrodes: a transmission electrode  401,  a reception electrode  402  and a shielding electrode  403.  The shielding electrode  403  shields the transmission electrode  401  and the reception electrode  402  from each other in terms of high-frequency and is constantly earthed. A high-frequency voltage is applied to the transmission electrode  401  from a high-frequency oscillation circuit  410.  A high-frequency voltage depending upon the magnitude of the electrostatic capacity between the electrodes  401  and  4023  is outputted from the reception electrode  402.  The high-frequency voltage outputted from the reception electrode  402  is converted into a DC voltage by a detection circuit  420.  The presence or absence or the amount of a substance is determined based on the magnitude of the DC voltage produced in the detection circuit  420.

FILED OF THE INVENTION

[0001] This invention relates to a capacitance-coupled sensor and amethod for detecting a substance using the capacitance-coupled sensor.

BACKGROUND OF THE INVENTION

[0002] Among sensors, there are capacitance-coupled sensors, namelycapacitance-coupled (electrostatic capacity) sensors using a condenser(capacitor). JP-A-2000-80703 discloses a sensor using acapacitance-coupled sensor for detecting the human body sitting on atoilet seat of a human body private part washing device. The sensordisclosed in the official gazette has a sensor unit comprising adetection electrode and an earth electrode for capacitive coupling, anda protection electrode interposed between the detection electrode andthe earth electrode, and the electrodes are insulated from each other.The electrostatic capacity between the detection electrode and the earthelectrode is used to set the oscillation frequency of a high-frequencyoscillator, and a change in the electrostatic capacity caused byapproach of a human body is obtained as a change in the oscillationfrequency (final output signal) from the oscillation circuit. Theprotection electrode is provided to reduce the electrostatic capacitypossessed by the sensor itself.

[0003] However, the sensor disclosed in the official gazette requires aspecial device for detecting frequency since the output signal obtainedfrom it a signal representing a change in frequency, which is notcommon. Also, the sensor disclosed in the official gazette is to detectthe presence or absence of a substance that is a human body and is notintended to detect changes in the amount of a substance such as a liquidin a continuously variable manner.

[0004] This invention has been made in view of the above circumstancesand it is, therefore, an object of this invention to provide acapacitance-coupled sensor from which a general DC voltage signal isobtained and a method for detecting a substance using thecapacitance-coupled sensor.

DESCRIPTION OF THE INVENTION

[0005] In accomplishing the above object, a transmission electrode and areception electrode adapted to be capacitively coupled to each other areused as an electrical resistance for a high-frequency voltage in thisinvention. To prevent the high-frequency voltage from leaking betweenthe transmission electrode and the reception electrode, a shieldingelectrode is interposed between the transmission electrode and thereception electrode. A high-frequency voltage as an output from thereception electrode is converted into a DC voltage by detection.

[0006] More specifically, the following solution is adopted in thedevice of this invention. Namely, as described in claim 1, thecapacitance-coupled sensor comprises:

[0007] a sensor unit having a transmission electrode, a receptionelectrode capacitively couplable to the transmission electrode, and ashielding electrode interposed between the transmission electrode andthe reception electrode for shielding the transmission electrode and thereception electrode from each other,

[0008] a high-frequency oscillator interposed between the transmissionelectrode and the shielding electrode for applying a high-frequencyvoltage to the transmission electrode; and

[0009] a detector interposed between the reception electrode and theshielding electrode for converting a high-frequency voltage outputtedfrom the reception electrode into a DC voltage.

[0010] The electrostatic capacity between the transmission electrode andthe reception electrode differs depending upon whether there is asubstance across the electrodes, and the difference in the electrostaticcapacity can be obtained based on the magnitude of a DC voltage detectedby the detector (to determine the presence or absence of the substance,which corresponds to claim 2). When the amount of a substance existingacross the transmission electrode and the reception electrode changes,the electrostatic capacity between the electrodes varies. The variationof the electrostatic capacity can be obtained based on the magnitude ofa DC voltage detected by the detector (to determine the amount of thesubstance, which corresponds to claim 16).

[0011] The following solutions can be combined with above solution asthe base.

[0012] The capacitance-coupled sensor may further comprise a comparatorfor comparing an output voltage from the detector with a specifiedthreshold voltage and outputting the comparison result (whichcorresponds to claim 3). In this case, the presence or absence of thesubstance can be determined more easily based on the output from thecomparator.

[0013] The capacitance-coupled sensor may further comprise an insulatingwall member having an inner surface with which a substance comes intocontact, wherein the sensor unit is provided on an outer surface of orin the wall member (which corresponds to claim 4). In this case, thesensor unit does not have to be brought into contact with the substance.

[0014] The wall member may serve as a wall member of a vessel or apiping system (which corresponds to claim 5). In this case, the presenceor absence of a substance in the vessel or the piping system can bedetected without bringing the sensor unit into contact with thesubstance.

[0015] The sensor unit may be constituted of at least three conductivewires extending in parallel to each other at small intervals as a whole(which corresponds to claim 6). In this case, the electrodes can beformed of conductive wires with ease and the substance can be passedthrough the gaps between the electrodes.

[0016] The capacitance-coupled sensor may be configured as follows:

[0017] the plurality of conductive wires are divided into first to thirdgroups each having a plurality of conductive wires,

[0018] a plurality of conductive wires in the first group serving as aplurality of transmission electrodes,

[0019] a plurality of conductive wires in the second group serving as aplurality of reception electrodes, and

[0020] a plurality of conductive wires in the third group serving as aplurality of shielding electrodes,

[0021] the conductive wires serving as shielding electrodes beingarranged between each of conductive wires serving as transmissionelectrodes and each of the conductive wires serving as receptionelectrodes,

[0022] the conductive wires serving as transmission electrodes beingelectrically connected with each other at one end,

[0023] the conductive wires serving as the reception electrodes beingelectrically connected with each other at one end, and

[0024] the conductive wires serving as shielding electrodes beingelectrically connected with each other at one end (which corresponds toclaim 7). In this case, the area for detecting the substance can bewidened with a simple structure. Also, the number of electricalconnections to the sensor unit can be the requisite minimum of three.

[0025] Each of the conductive wires is coated with an insulating coatingmaterial (which corresponds to claim 8). In this case, the insulationbetween the conductive wires can be easily achieved. Also, the sensorunit can be formed using a commercially available coated wire with ease.

[0026] The capacitance-coupled sensor may further comprise spacermembers provided at both longitudinal ends of the conductive wires formaintaining the intervals between the conductive wires (whichcorresponds to claim 9). In this case, the conductive wires can bereliably kept separated at specified intervals.

[0027] The capacitance-coupled sensor may be configured as follows:

[0028] each of the transmission electrode, the reception electrode andthe shielding electrode is constituted of a plurality of conductivewires,

[0029] the plurality of conductive wires constituting the transmissionelectrode extending in parallel to each other at specified intervals ona first plane,

[0030] the plurality of conductive wires constituting the receptionelectrode being located on a second plane generally parallel to thefirst plane and extending in a direction crossing the conductive wiresconstituting the transmission electrode at small intervals,

[0031] the plurality of conductive wires constituting the shieldingelectrode being located between the first and second planes andextending in a direction crossing the plurality of conducive wiresconstituting the transmission electrode and the plurality of conducivewires constituting the reception electrode,

[0032] whereby the conductive wires constituting the transmissionelectrode, the conductive wires constituting the reception electrode,and the conductive wires constituting the shielding electrode aremutually crossed at a multiplicity of points as seen in a directionperpendicular to the first plane so that the sensor unit can be in theform of a sheet with a multiplicity of mesh apertures as a whole (whichcorresponds to claim 10). In this case, the area for detecting thesubstance can be significantly widened with a simple structure. Also, amultiplicity of detection sections each comprising a transmissionelectrode, a reception electrode and a shielding electrode can beformed.

[0033] The capacitance-coupled sensor may be configured as follows:

[0034] the conductive wires constituting the transmission electrode areelectrically connected to each other at one end,

[0035] the conductive wires constituting the reception electrode areelectrically connected to each other at one end, and

[0036] the conductive wires constituting the shielding electrode areelectrically connected to each other at one end (which corresponds toclaim 11). In this case, the number of electrical connections to thesensor unit can be the requisite minimum of three.

[0037] The capacitance-coupled sensor may be configured as follows:

[0038] when the plurality of conductive wires constituting thetransmission electrode, the plurality of conductive wires constitutingthe reception electrode and the plurality of conductive wiresconstituting the shielding electrode are represented as first to thirdconductive wire group, respectively,

[0039] two of the first to third conductive wire groups extendperpendicular to each other and the other conductive wire group extendsat an angle of about 45° to the two conductive wire groups (whichcorresponds to claim 12). This feature is useful to improve the diagonalstrength of the sensor unit having a net or lattice structure whilesecuring its lateral and longitudinal strength.

[0040] Each of the conductive wires may be coated with an insulatingcoating material (which corresponds to claim 13). In this case, theinsulation between the electrodes can be achieved with ease using acommercially available coated wire.

[0041] The capacitance-coupled sensor may further comprise spacermembers provided at both longitudinal ends of the conductive wires formaintaining the intervals between the conductive wires (whichcorresponds to claim 14). This feature is useful to maintain theintervals, in other words, the positional relations, between theconductive wires reliably.

[0042] The capacitance-coupled sensor may be configured as follows:

[0043] the spacer members are arranged in the form of a ring with alarge opening in the center, and

[0044] the conductive wires extend across the opening of the spacermembers with their longitudinal ends fixed to the spacer members (whichcorresponds to claim 15). In this case, it is possible to securesufficient rigidity of the spacer members with a simple structure. Also,it is advantageous that the spacer members do not interfere with thesubstance passing through the gaps (mesh apertures) among the conductivewires.

[0045] The capacitance-coupled sensor may further comprise a vessel forcontaining a substance,

[0046] wherein the sensor unit is elongated in the direction in whichthe level of the substance in the vessel changes, and

[0047] at least the part of the vessel where the sensor unit is locatedand around it have insulation (which corresponds to claim 17). In thiscase, the amount of the substance in the vessel can be detected in acontinuously variable manner.

[0048] The sensor unit may be provided on an outer surface of or in awall of the vessel (which corresponds to claim 18). In this case, theamount of the substance in the vessel can be detected without bringingthe sensor unit in contact with the substance.

[0049] The sensor unit may be located outside and in the vicinity of thevessel (which corresponds to claim 19). In this case, the amount of thesubstance in the vessel can be detected without directly attaching thesensor unit to the vessel.

[0050] The capacitance-coupled sensor may be configured as follows:

[0051] a plurality of sensor units are provided, transmission electrodesof the sensor units are connected in parallel to the high-frequencyoscillator,

[0052] reception electrodes of the sensor units are connected inparallel to the detector, and

[0053] a selection unit for selectively connecting one of thetransmission electrode to the high-frequency oscillator is provided(which corresponds to claim 20). In this case, only one high-frequencyoscillator and only one detector are required for the plurality of thesensor units.

[0054] The capacitance-coupled sensor may be configured as follows:

[0055] a plurality of sensor units are provided, transmission electrodesof the sensor units are connected in parallel to the high-frequencyoscillator,

[0056] reception electrodes of the sensor units are connected inparallel to the detector, and

[0057] a selection unit for selectively connecting one of the receptionelectrode to the detector is provided (which corresponds to claim 21).In this case, only one high-frequency oscillator and only one detectorare required for the plurality of the sensor units.

[0058] The transmission electrode, the reception electrode and theshielding electrode may be supported by a support of an insulatingsynthetic resin (which corresponds to claim 22). In this case, theattachment of the electrodes can be made using the support with theelectrodes maintained in a specified positional relation.

[0059] The capacitance-coupled sensor may be configured as follows:

[0060] the transmission electrode, the reception electrode and theshielding electrode are so thin as to be able to be bent easily, and

[0061] the support is flexible so that it can be bent easily togetherwith the transmission electrode, the reception electrode and theshielding electrode (which corresponds to claim 23). In this case, theelectrodes, namely the support, can be attached to a curved surface orthe like with ease.

[0062] The capacitance-coupled sensor may be configured as follows:

[0063] the transmission electrode, the reception electrode and theshielding electrode are embedded in the support, and conductive wiresextending from the transmission electrode, reception electrode andshielding electrodes extend out of the support (which corresponds toclaim 24). This feature is useful to protect the electrode, in otherwords, to improve the service lives of the electrodes. Connections tothe electrodes can be made using the conductive wires extending out ofthe support with ease.

[0064] The high-frequency oscillator may be a clock incorporated in acomputer (which corresponds to claim 25). In this case, the clock of thecomputer can be effectively used as the high-frequency oscillator.

[0065] The substance may be a living body, excrement of a living body,gas, liquid, solid matter, powder, particulate matter or gelatinoussubstance (which corresponds to claim 26). The substances listed aboveare only example and the range (types) of substances as detectingobjects is vary wide.

[0066] The capacitance-coupled sensor may further comprise an excrementcup to be attached to a patient for receiving excrement of the patient,

[0067] wherein the sensor unit is provide on an outer surface of theexcrement cup or an outer surface of an excrement discharge passageextending from the excrement cup (which corresponds to claim 27). Inthis case, detection of the excrement can be performed while reliablypreventing the sensor from being contaminated by the excrement.

[0068] The capacitance-coupled sensor may further comprise an excrementcup to be attached to a patient for receiving at least excrement of thepatient, and

[0069] a stool discharge passage for discharging at least stool from theexcrement cup with an in-cup opening which opens upward in the excrementcup,

[0070] wherein the sensor unit is placed across the in-cup opening sothat stool excreted by the patient can be received by the sensor unit,and

[0071] the stool on the sensor unit is passed through the sensor unitwhen the stool discharge passage is subjected to suction (whichcorresponds to claim 28). In this case, the excrement excreted into theexcrement cap can be reliably detected by the sensor unit having a widedetection area. Also, stool excreted into the excrement cup ispulverized by being passed through gaps among the conductive wiresconstituting the sensor unit and pulverized. This feature is useful toprevent the stool from clogging in the discharge passage.

[0072] In accomplishing the above object, this invention adopts thefollowing solution. As described in claim 29, the method of thisinvention is the method for detecting a substance using acapacitance-coupled sensor comprising a sensor unit having atransmission electrode, a reception electrode adapted to be capacitivelycoupled to the transmission electrode, and a shielding electrodeinterposed between the transmission electrode and the receptionelectrode for shielding the transmission electrode and the receptionelectrode from each other, comprising the steps of:

[0073] applying a high-frequency voltage across the transmissionelectrode and the reception electrode,

[0074] converting a high-frequency voltage outputted from the receptionelectrode into a DC voltage, and

[0075] detecting at least either of the presence or absence or theamount of the substance based on the magnitude of the DC voltage.

[0076] The presence or absence or the amount of the substance can bethereby detected with ease based on the magnitude of the DC voltage.

[0077] According to this invention, it is possible to detect thepresence or absence or the amount of a substance can be obtained varyeasily based on the magnitude of a DC voltage and provide a sensor withhigh versatility.

BRIEF DESCRIPTION OF THE DRAWINGS

[0078]FIG. 1 is a view illustrating an example of a circuit of acapacitance-coupled sensor according to this invention;

[0079]FIG. 2 is a graph schematically illustrating the manner ofhigh-frequency oscillation of a high-frequency oscillator shown in FIG.1;

[0080]FIG. 3 is a characteristic curve showing the relation with theelectrostatic capacity;

[0081]FIG. 4 is an enlarged view of a section of the characteristiccurve shown in FIG. 3 where the electrostatic capacity is small;

[0082]FIG. 5 is a characteristic curve showing an example of therelation between the amount of water in a measuring vessel and theoutput voltage;

[0083]FIG. 6 is a plan view illustrating an example in which a pluralityof conductive wires are arranged in parallel to form a sensor unit;

[0084]FIG. 7 is a cross-sectional view taken along the line X7-X7 inFIG. 6;

[0085]FIG. 8 is a cross-sectional view of the conductive wire;

[0086]FIG. 9 is a plan view illustrating an example of a sensor unitcomprising a plurality of conductive wires arranged in a net (lattice)structure;

[0087]FIG. 10 is a cross-sectional view taken along the line X10-X10 inFIG. 9;

[0088]FIG. 11 is a simplified cross-sectional side view illustrating anexample in which the sensor unit is provided on a fuel tank;

[0089]FIG. 12 is an enlarged left side view of FIG. 11;

[0090]FIG. 13 is a characteristic curve showing the relation between theamount of fuel and the output voltage from a detection circuit;

[0091]FIG. 14 is a perspective view illustrating an example in whichelectrodes are held in a support;

[0092]FIG. 15 is cross-sectional view of FIG. 14;

[0093]FIG. 16 is a cross-sectional view illustrating a modification ofFIG. 15;

[0094]FIG. 17 is a cross-sectional view of an essential part of anexample in which the support is embedded in a wall member of a vessel;

[0095]FIG. 18 is view illustrating an example of a circuit suitable fora sensor having a plurality of sensor units;

[0096]FIG. 19 is a perspective view of an essential part of an examplein which the amounts of inks in a plurality of ink tanks areindividually detected;

[0097]FIG. 20 is a backside view of FIG. 19, looking from the side ofsupports;

[0098]FIG. 21 is a side view of FIG. 19, looking in the arrangementdirection of the ink tanks;

[0099]FIG. 22 is a view illustrating an example of a circuit in whichoutputs from a plurality of sensors are processed in a one-chipmicrocomputer;

[0100]FIG. 23 is a side view illustrating a state where the senor unitis attached to an excrement disposal device;

[0101]FIG. 24 is a left side view of FIG. 23;

[0102]FIG. 25 is a side view illustrating a state where the excrementdisposal device is attached to a patient in a sitting position;

[0103]FIG. 26 is a cross-sectional side view of an essential part of theexcrement disposal device;

[0104]FIG. 27 is a left side view of FIG. 26;

[0105]FIG. 28 is a right side view of FIG. 26;

[0106]FIG. 29 is a cross-sectional view taken along the line B1-B1 inFIG. 26;

[0107]FIG. 30 is a cross-sectional view taken along the line B2-B2 inFIG. 26;

[0108]FIG. 31 is a cross-sectional view taken along the line B3-B3 inFIG. 26;

[0109]FIG. 32 is a circuit diagram of a stool sensor;

[0110]FIG. 33 is a block diagram of a control unit of the excrementdisposal device;

[0111]FIG. 34 is a flowchart of the control unit;

[0112]FIG. 35 is a cross-sectional side view illustrating anotherexample in which a sensor unit is provided in an excrement cup;

[0113]FIG. 36 is a cross-sectional view taken along the line B5-B5 inFIG. 35;

[0114]FIG. 37 is a side view illustrating another example in which asensor unit is provided in relation to the excrement cup;

[0115]FIG. 38 is a top plan view of a holding clip shown in FIG. 37; and

[0116]FIG. 39 is a right side view of FIG. 38.

BEST MODE FOR CARRYING OUT THE INVENTION

[0117] Description of FIG. 1 to FIG. 5

[0118]FIG. 1 shows an example of a circuit of a capacitance-coupledsensor according to this invention. Designated as 400 is a sensor unit.The sensor unit 400 has three electrodes: a transmission electrode 401,a reception electrode 402 and a shielding electrode 403. The electrodes401 to 403 are made of a conductive material (such as a thin plate ofcopper). The electrodes 401 to 403 are arranged in parallel to eachother at specified small intervals. Namely, the space between thetransmission electrode 401 and the shielding electrode 403, and thespace between the reception electrode 402 and the shielding electrode403 form insulating layers (an insulating material may be interposedbetween the electrodes for insulation).

[0119] The transmission electrode 401 and the reception electrode 402are adapted to be capacitively coupled to each other and constitute acapacitor in conjunction with each other. The shielding electrode 403shields the transmission electrode 401 and the reception electrode 402from each other in terms of high-frequency as described later and isconstantly earthed.

[0120] A high-frequency voltage (a voltage with a frequency of, forexample, 2 MHz) is applied to the transmission electrode 401 from ahigh-frequency oscillation circuit (high-frequency oscillation unit,high-frequency oscillation means) 410. Namely, the high-frequencyoscillation circuit 410 is formed between the transmission electrode 401and the shielding electrode 403. A high-frequency voltage is outputtedfrom the reception electrode 402 as described later. The high-frequencyvoltage outputted from the reception electrode 402 is converted into aDC voltage by a detection circuit (detection unit, detection means) 420formed between the reception electrode 402 and the shielding electrode403. The DC voltage outputted from the detection circuit 420 can betaken out as a potential difference between output terminals 421 and 422(422 is an earth terminal).

[0121] The DC voltage produced by the detection circuit 420 is inputtedinto a comparison circuit (comparison unit, comparison means) 430 whennecessary. The comparison circuit 430 comprises a comparator 431, whichcompares an inputted DC voltage with a specified threshold voltage ERand outputs a signal (ON signal or OFF signal) based on the result ofthe comparison. The comparison circuit 430 (comparator 431) ispreferably used in detecting the presence or absence of a substance andmay be omitted in detecting the amount of a substance in a continuouslyvariable manner.

[0122] The high-frequency oscillation circuit 410 has a Schmitt circuit(hysteresis comparator) 411. The Schmitt circuit 411 outputs a specifiedfixed voltage +Eo when the input voltage into its input port all becomesa specified upper limit threshold voltage EH or higher. The Schmittcircuit 411 outputs a specified fixed voltage −Eo when the input voltageinto its input port all becomes a specified lower limit thresholdvoltage EL or lower (0<EL<EH<Eo). The input port all is earthed via abuffering resistor 412 and a capacitor 413. The output voltage from theSchmitt circuit 411 is inverted by an inverter 414 and applied to thetransmission electrode 401. The output voltage after having beeninverted by the inverter 414 is returned to a feedback position a12between the resistor 412 and the capacitor 413 via a feedback resistor415.

[0123] Let VH be the voltage at the feedback position a12 at the timewhen the voltage at the input port all is the upper limit thresholdvoltage EH. Let VL be the voltage at the feedback position a12 at thetime when the voltage at the input port a11 is the lower limit thresholdvoltage EL. In this case, since the voltage at the feedback position 12a varies between VH and VL, the output voltage from the Schmitt circuit411 is in the form of square waves (high-frequency voltage) which variesbetween +Eo and −Eo as shown in FIG. 2. In FIG. 1, a power sourcecircuit for operating the Schmitt circuit 411 is not shown.

[0124] The reason why the square waves as shown in FIG. 2 are obtainedis described. When the operation of the Schmitt circuit 411 is startedfrom the initial state where the capacitor 413 has been discharged (thevoltage at the feedback position a12 is zero), the Schmitt circuit 411outputs −Eo. The output voltage of −Eo outputted from the Schmittcircuit 411 is inverted into +Eo by the inverter 414. The output voltageof +Eo from the inverter 414 is applied to the capacitor 413 via afeedback resistor 415, whereby the capacitor 413 starts charging and thevoltage at the feedback position a12 is gradually increased. When thevoltage at the feedback position a12 is increased to VH, the Schmittcircuit 411 outputs +Eo. When the Schmitt circuit 411 outputs +Eo, sincethe output of the inverter 414 becomes −Eo, the charged capacitor 413start discharging to the feedback resistor 415. By gradual discharge ofthe capacitor 413, the voltage at the feedback position a12 is graduallydecreased to VL. The Schmitt circuit 411 thereby outputs −Eo. When thecapacitor 413 is repeatedly charged and discharged as described above,the voltage at the feedback position a12 varies between VH and VL,whereby the output of the Schmitt circuit 411 is varied between +Eo and−Eo (square waves).

[0125] As described above, when the transmission electrode 401 and thereception electrode 402 are capacitively coupled to each other while ahigh-frequency voltage is applied to the transmission electrode 401 (forexample, when a substance such as a human approaches the transmissionelectrode 401 and the reception electrode 402), a high-frequency voltageis outputted from the reception electrode 402. The magnitude of thehigh-frequency voltage to be outputted from the reception electrode 402depends upon the electrostatic capacity between the electrodes 401 and402. The shielding electrode 403 prevents the high-frequency voltageapplied to the transmitting electrode 401 from leaking directly to thereception electrode 402.

[0126] The detection circuit 420 has two Schottky barrier diodes 423 and424, by which the high-frequency voltage outputted from the receptionelectrode 402 is subjected to voltage doubler rectification. The highfrequency voltage after the voltage doubler rectification is smoothedinto a DC voltage by the resistor 425 and a capacitor 426. In FIG. 1,“A” shows an example of the waveform of the high-frequency voltageapplied to the transmission electrode 401. In FIG. 1, “B” shows anexample of the waveform of the high-frequency voltage outputted from thereception electrode 402. In FIG. 1, “C” shows an example of the waveformafter being smoothed into a DC voltage.

[0127] The comparison circuit 430 (comparator 431) compares the DCvoltage (input voltage) outputted from the detection circuit 420 withthe specified threshold voltage ER. The comparison circuit 430 outputs,for example, a specified ON signal only when the input voltage is higherthan the threshold voltage ER.

[0128]FIG. 3 is a characteristic curve showing the relation between themagnitude of the electrostatic capacity between the transmissionelectrode 401 and the reception electrode 402 and the DC output voltagefrom the detection circuit 420 (the potential difference across theelectrodes 421 and 422). As shown in FIG. 3, there is a non-linearrelation between the electrostatic capacity and the DC output voltage asa whole. FIG. 4 shows the characteristic shown in FIG. 3 within a rangewhere the electrostatic capacity is small. As is clear from FIG. 4, itis understood that there is a linear relation between the electrostaticcapacity and the DC output voltage when the electrostatic capacity issmall.

[0129]FIG. 5 shows the relation between the amount of water in acommercially available measuring vessel of a (insulating) syntheticresin and the output voltage from the detection circuit 420 measuredwith the sensor unit 400 attached to an outer surface of the measuringvessel, as shown in FIG. 1. As is clear from FIG. 5, the amount of waterin the measuring vessel can be obtained based on the output voltage. Thesensor unit 400 (the electrodes 401 to 403 thereof) is placed such thatit extends in the direction in which the level of water in the vesselmoves (vertical direction).

[0130] Examples of the substance for capacitively coupling thetransmission electrode 401 and the reception electrode 402 include aliving body; excrement of a living body; liquids such as water, gasolineand chemical liquid; gases such as natural gas, hydrogen gas andmanufactured gas; powders such as rice powder and flour; solid matterssuch as concrete products, wood products and synthetic resin products;particulate matters; and gelatinous substances. In other words,substances which do not capacitively couple the transmission electrode401 and the reception electrode 402 are exceptional. Namely, thisinvention has wide industrial applications for detecting the presence orabsence, or the amount of various types of substances. The sensor unit400 may not be in contact with the substance to be detected (or may beused in contact therewith).

[0131] Description of FIG. 6 to FIG. 8

[0132]FIG. 6 to FIG. 8 show a modification of the sensor unit 400. Asensor unit 400B in this example substantially has a plurality of setsof sensor unit 400 formed using a plurality of conductive wires 500.Each of the conductive wires 500 used comprises a conductive wirematerial 501 such as a copper wire coated entirely with a coatingmaterial 502 of a synthetic resin as an insulating material as shown inFIG. 8.

[0133] The plurality of conductive wires 500 are arranged almost inparallel to one another at small intervals. In this embodiment, thirteenconductive wires 500 are used in total. In FIG. 6, the conductive wires500 are designated as 500 a, 500 b, . . . , and 500 m from top to bottomfor identification purpose. Among them, every other conductive wire inthe arranging direction of the conductive wires, including the ones atthe both ends, (the conductive wires 500 a, 500 c, 500 e, 500 g, 500 i,500 k and 500 m, shown in black for clarity) serve as shieldingelectrodes 403. The three conductivity wires 500 b, 500 f, 500 j (shownwith hatching for clarity) serve as transmission electrodes 401. Thethree conductivity wires 500 d, 500 h, 500 l (shown in white forclarity) serve as reception electrodes 402. As described above,conductive wires serving as shielding electrodes are located betweenconductive wires serving as transmission electrodes and conductive wiresserving as reception electrodes adjacent to each other. The conductivewires located on the outermost side in the arranging direction of theplurality of conductive wires also serve as shielding electrodes.

[0134] The plurality of (three in this embodiment) conductive wires 500b, 500 f and 500 j serving as transmission electrodes are electricallyconnected to each other at one end by a connection wire 510. Theplurality of (three in this embodiment) conductive wires 500 d, 500 hand 500 l serving as reception electrodes are electrically connected toeach other at one end by a connection wire 520. The plurality of (sevenin this embodiment) conductive wires 500 a, 500 c, 500 e, 500 g, 500 i,500 k and 500 m serving as shielding electrodes are electricallyconnected to each other at one end by a connection wire 530.

[0135] Both ends of the plurality of conductive wires 500 (500 a to 500m) are fixed to spacer members 540. Each of the spacer members 540 ismade of an insulating material (such as a synthetic resin) and has asurface with grooves 541 for receiving the conductive wires in anisolated manner (the number of the grooves 541 is the same as the numberof the conductive wires). By the spacer members 540, the conductivewires 500 are kept separated at specified small intervals. The spacermembers 540 have fixing holes 542 so that the sensor unit 400B can befixed to a specified member using (the fixing holes 542 of) the spacermembers 540.

[0136] The sensor unit 540B as described above is mainly used to detectthe presence or absence of a substance. For example, it is provided inan excrement cup attached to a human body. In this case, stool or urineexcreted by a patient comes into contact with a wire serving as atransmission electrode and a wire serving as a reception electrodesimultaneously, the capacitive coupling is varied, whereby the presenceof the stool or urine can be detected. Since sensor unit 540Bsubstantially has a plurality of sets of sensor units 400, which areprovided over a wide area, the stool or urine can be reliably detected.The sensor has various other applications. For example, it may beinstalled outdoors to detect rainfall.

[0137] At least the portion of the sensor unit 400B between the twospacer members 540 has flexibility. The spacer members 540 may be formedof a flexible material so that the entire portion of the sensor unit400B can have flexibility.

[0138] Description of FIG. 9 and FIG. 10

[0139]FIG. 9 and FIG. 10 show a modification of the sensor unit 400. Asensor unit 400C in this example substantially has a plurality of setsof sensor unit 400 formed using a plurality of conductive wires 500.Each of the conductive wires 500 used comprises a conductive wirematerial 501 such as a copper wire coated entirely with a coatingmaterial 502 of a synthetic resin as an insulating material as shown inFIG. 8 (the same as that in the example shown in FIG. 6 to FIG. 8).

[0140] In FIG. 9, conductive wires serving as transmission electrodes401 are designated as 550, conductive wires serving as receptionelectrodes 402 are designated as 560, and conductive wires serving asshielding electrodes 403 are designated as 570 to distinguish theplurality of conductive wires 500. The conductive wires 550 serving astransmission electrodes are located on a specified plane (first plane,which is in parallel to the plane of FIG. 9) and extend generally inparallel to each other in the vertical direction of FIG. 9 at smallintervals. The conductive wires 550 are electrically connected to eachother at one end by a connection wire 551.

[0141] The conductive wires 570 serving as shielding electrodes arelocated on the conductive wires 550 serving as transmission electrodes(on a second plane, which is in parallel to the first plane) and extendgenerally in parallel to each other in the lateral direction of FIG. 9at small intervals. The conductive wires 570 are electrically connectedto each other at one end by a connection wire 571.

[0142] The conductive wires 560 serving as reception electrodes arelocated on the conductive wires 550 and 570 and extend in a diagonaldirection of FIG. 9. In this embodiment, the conductive wires 560 extendat an angle of almost 45 degrees to the conductive wires 550 and 5780.The conductive wires 560 are electrically connected to each other at oneend by a connection wire 561.

[0143] The conductive wires 550, 560 and 570 forms a multiplicity ofintersections in a matrix manner as shown in FIG. 9 (plan view), andeach of the multiplicity of intersections constitute a sensor unit 400.One of the intersections is shown in FIG. 10 in detail. At theintersections, the coating materials 502 of the conductive wires 550,560 and 570 are fusion-bonded or bonded with an adhesive so that theycan be integrated and cannot be displaced. As described above, thesensor unit 400C is in the form of a thin net or lattice sheet with amultiplicity of mesh apertures (gaps).

[0144] The sensor unit 400C has a spacer member 580 around it. Thespacer member 580 is formed of an insulating material such as asynthetic resin. The spacer member 580 has a ring shape with a largeopening 581 in the center as a whole (ring shape with almost squareinner and outer periphery). The conductive wires 550, 560, and 570extend across the opening 581. Both ends of the conductive wires 550,560, and 570 are fixed to the spacer member 580 so that the conductivewires 550, 560, and 570 cannot be displaced.

[0145] The sensor unit 400C as described above can be used in the samemanner as the sensor unit 400B shown in FIG. 6. Although not shown, thespacer member 580 may have fixing holes, or may have flexibility. Theextending directions of the conductive wires serving as the electrodesshown in FIG. 8 are illustrative. The conductive wires may extend in anydirection. For example, the conductive wire 550 serving as transmissionelectrodes and the conductive wires 560 serving as reception electrodes560 may be perpendicular to each other, or the conductive wire 560serving as reception electrodes and the conductive wires 570 serving asshielding electrodes 560 may be perpendicular to each other (as long asthe conductive wires serving as shielding electrodes are located betweenthe conductive wires serving as transmission electrodes and theconductive wires serving as receiving electrodes).

[0146] Description of FIG. 11 to FIG. 13

[0147]FIG. 11 and FIG. 12 show an example in which the sensor unit 400of the capacitance-coupled sensor shown in FIG. 1 is used to detect theamount of fuel in a fuel tank of a vehicle. A fuel tank 600 (wallmembers forming the exterior thereof) is made of a fiber-reinforcedplastic as an insulating material. The sensor unit 400, which iselongated vertically, is attached along mist of the vertical length ofan outer surface of the fuel tank 600. When the amount of fuel in thefuel tank 600 is changed, the electrostatic capacity between thetransmission electrode 401 and the reception electrode 402 of the sensorunit 400 is changed, whereby the amount of fuel can be detected (basedon the potential difference across the terminals 421 and 422 shown inFIG. 1).

[0148] When there is no linear relation between the magnitude of theoutput voltage and the amount of fuel in the example shown in FIG. 11,the relation therebetween is stored (in a recording medium such as aRAM) as a table as shown in FIG. 13 so that the amount of fuel can bedetermined by comparing the detected voltage with the table value (thisis applicable not only to the detection of fuel amount but also to anycase of detecting the amount of a substance).

[0149] Description of FIG. 14 to FIG. 17

[0150]FIG. 14 and FIG. 15 show an example in which the sensor unit 400(the electrodes 401, 402 and 403 thereof) is embedded in a support 610of an insulating material such as a synthetic resin. Conductive wires611, 612 and 613 extending from the electrodes 401, 402 and 403,respectively, extend out of the support 610. Since the sensor unit 400is entirely covered, it has strength against external forces and is easyto attach since the attachment can be made via the support 610. Thesupport 610 may be made of a flexible material so that the entireportion can have flexibility. The electrodes 401 to 403 and the support610 can be made as thin as a film as a whole. When there is apossibility that a large voltage is used or large external forces areapplied, or when the sensor must have durability for outdoor use, it isadvisable to increase the coating thickness of the support 610. Only oneside (upper side in FIG. 15, for example) surfaces of the electrodes 401to 403 as the detection surfaces thereof may be exposed (to improvesensitivity).

[0151] As shown in FIG. 16, an electrode 404 for preventing noise may beadditionally embedded in the support 610. When one side of the support610 (the upper side in FIG. 15) serves as a detection surface, theelectrode 404 is located on the other side of the electrodes 401 to 403.The electrode 404 is electrically connected to the shielding electrode403. When the electrode 404 for preventing noise is provided, it ispossible to prevent capacitive coupling between the transmissionelectrode 401 and the reception electrode 402 at the time when asubstance which is not a detecting object approaches the other side ofthe support 610. The electrode 404 for preventing noise may be used whenthe electrodes 401 to 403 are not supported in the support 610.

[0152]FIG. 17 shows an example in which the electrodes 401 to 403supported in the support 610 is embedded in a wall member of a vessel615 such as a measuring vessel. The wall members constituting theexterior of the vessel 615 are made of an insulating material such as asynthetic resin. When the part in which the support 610 (the electrodes401 to 403) is located and around it have insulation, the vessel 615 maybe made of any material. The electrodes 401 to 403, namely the support610, can be embedded in forming the vessel 615 by injection molding.

[0153] Only the conductive wires 611 to 613 for the electrodes extendout of the wall member of the vessel 615. The electrodes 401 to 403extend in the direction in which the level of the substance in thevessel 615 (liquid such as water) moves (in a vertical direction). Theamount of the substance in the vessel 615 can be detected in acontinuously variable manner based on the magnitude of the DC voltageoutputted from the detection unit 420.

[0154] Description of FIG. 18 to FIG. 21

[0155]FIG. 18 shows an example suitable for a sensor having a pluralityof sensor units 400, one high-frequency oscillation circuit 410 and onedetection circuit 420. Namely, FIG. 18 shows an example in which thepresence or absence or the amounts of substances can be independentlydetected by plural number of sensor units 400. In FIG. 18, designated asU10 is a controller constituted using a microcomputer. The controllerU10 may be a personal computer. The high-frequency oscillation circuit410 is constituted using (the oscillation frequency of) a clock of thecontroller U10 (amplifies the output from the clock and outputs it whennecessary).

[0156] In this embodiment, there are four sensor units 400, which aredesignated as 400 a, 400 b, 400 c and 400 d for identification purpose.The sensor units 400 (400 a to 400 d) are connected in parallel to eachother to the clock constituting the high-frequency oscillation circuit410 in the controller U10. The sensor units 400 (400 a to 400 d) areconnected in parallel to each other to the detection circuit 420.Electromagnetic switches SW11, SW12, SW13 and SW14 are connected betweeneach of the sensor units 400 and the detection circuit 420. The switchesSW11 to SW14 are independently opened and closed by the controller U10(when one of the switches is turned on, the other switches are turnedoff). The switches SW11 to SW14 constitutes a selection unit SW(selection means).

[0157] When only the switch SW11 is turned on by the controller U10,only the sensor unit 400 a provides an output to the detection circuit420, whereby the presence or absence or the amount of the substance as adetecting object of the sensor unit 400 a is detected. When only theswitch SW12 is turned on, the presence or absence or the amount of thesubstance as a detecting object of the sensor unit 400 b is detected.When only the switch SW13 is turned on, the presence or absence or theamount of the substance as a detecting object of the sensor unit 400 cis detected. When only the switch SW14 is turned on, the presence orabsence or the amount of the substance as a detecting object of thesensor unit 400 d is detected. The number of the sensor units 400 can bearbitrarily determined. The presence or absence or the amount of thesubstance detected can be displayed on a display unit 645.

[0158] As a modification of the device shown in FIG. 18, the selectionunit SW may be provided between the plurality of sensor units 400 (400 ato 400 d) and the high-frequency oscillation circuit 410. Also in thiscase, by turning on one of the switches, the presence or absence or theamount of the substance as the detecting object of the sensor unitcorresponding to the switch turned on is detected.

[0159]FIG. 19 to FIG. 21 show a specific example in which detection ofsubstances is performed using a plurality of sensor units 400 shown inFIG. 18. In this example, a plurality of ink tanks 651 to 654 aredetachably attached to an attachment base 655 in an ink jet printer. Theink tanks 651 to 654 contain different color inks and have an exteriorof an insulating synthetic resin. A sensor unit 400 supported in asupport 610 as shown in FIG. 14 and 15 is provided in the close vicinityof each of the ink tanks 651 to 654. The sensor units 400, namely thesupports 610, are integrated with the attachment base 655. Each sensorunit 400 extends in the direction in which the ink in the ink tankincreases or decreases (vertical direction).

[0160] When a controller incorporated in the ink jet printer constitutesthe controller U10 shown in FIG. 18. Using the plurality of sensor units400, the amounts of inks in the ink tanks 651 to 654 are independentlydetected. The detection results may be displayed on a display unit(corresponding to the display unit 645 shown in FIG. 18) of the ink jetprinter. Each sensor unit 400 does not have to detect the amount of theink in a continuously variable manner when it is only necessary to warnthat the amount of ink is reduced to a predetermined level.

[0161] In the case of a personal computer, the display of it can be usedas the display unit.

[0162] Description of FIG. 22

[0163]FIG. 22 shows an example in which outputs from a plurality ofsensor units 400 are processed by a one-chip microcomputer. In thisembodiment, detection circuits 420 are provided for each of the sensorunits 400. The one-chip microcomputer shown in FIG. 22 is incorporatedin a printer, for example, and can be used to detect the amounts of inksin a plurality of ink tanks shown in FIG. 19 to FIG. 20 individually.

[0164] In FIG. 22, designated as U20 is a one-chip microcomputer(HITACHI H8/3664, for example). The microcomputer U20 has a CPU 681, aRAM 682, a ROM 683, an oscillation circuit 684, an analogue multiplexer685, an A/D converter 686, and an I/O port 687. The sensor units 400 areconnected in parallel to the oscillation circuit 684. Outputs (DCvoltages) from the detection circuits 420 are individually inputted intothe analogue multiplexer 685. The shielding electrodes 403 are grounded.

[0165] In the RAM 682, an OS (operating system) for making the CPU 681perform a specified operation (control) is stored. In the ROM 683, datawhich are necessary when the CPU 681 performs the operation aretemporarily stored. The oscillation circuit 684 outputs a high-frequencyvoltage with a specified frequency (2 MHz, for example) using a clock(crystal oscillator). The analogue multiplexer 685 is an analogue switchfor selecting one output signal from output signals outputted from theplurality of detection circuits 420. The A/D converter 686 converts ananalogue signal from the analogue multiplexer into a digital signal. TheI/O port 687 outputs the digital signal produced in the A/D converter686 to the outside.

[0166] The one-chip microcomputer U20 performs the following operation.A high-frequency voltage is outputted from the oscillation circuit 684to the sensor units 400. Then, each sensor unit 400 outputs ahigh-frequency voltage according to its electrostatic capacity. Thehigh-frequency voltages from the sensor units 400 are converted into DCvoltages by corresponding detection circuits 420 and inputted into theanalogue multiplexer 685. The outputs from the detection circuits 420are designated as #1, #2, #3 and #4, respectively, in FIG. 22.

[0167] The analogue multiplexer 685 receives only one output (#1, forexample) of the outputs (#1, #2, #3 and #4) from the detection circuits420 and outputs it to the A/D converter 686. The output from theanalogue multiplexer 685 is finally outputted from the I/O port 687 tothe outside via the A/D converter 686. In FIG. 22, outputs correspondingto the outputs #1, #2, #3 and #4 from the I/O port 687 are designated as#1 a, #2 a, #3 a and #4 a, respectively.

[0168] In this embodiment, the analogue multiplexer 685 receives theoutputs from the detection circuits 420 in sequence at a specifiedsampling cycle (for example, receives in the order of #1, #2, #3, #4 insequence at a specified sampling cycle). In this embodiment, the outputfrom the I/O port 687 is provided when there is an output from the A/Iconverter 686. Thus, the outputs #1 a, #2 a, #3 a and #4 a according tothe outputs from the detection circuits 420 are provided in sequence ata specified cycle.

[0169] The timing at which the analogue multiplexer 685 receives theoutputs from the detection circuits 420 can be arbitrarily set. Forexample, the reception may be made in response to the operation of amanual switch (not shown) additionally provided. The output from the A/Oconverter 686 may be temporarily stored in the ROM 683 so that theoutput from the I/O port 687 can be provided at specified timing or inresponse to a specified manual operation.

[0170] Description of FIG. 23 to FIG. 34

[0171]FIG. 23 to FIG. 34 show an example in which the sensor of thisinvention is used for detection of excrement (stool or urine) in anexcrement cup attached to a patient. In the following description, thesensor unit 400 may be shown as sensor S1 or S2.

[0172] In FIG. 23 to FIG. 25, designated as 5 is a wearer, namely apatient, as A-1 is an excrement disposal device. The excrement disposaldevice A-1 has a stool receiving cup 10 and a urine receiving cup 25which are separately formed. The cups 10 and 25 are made of a plasticmaterial, for example. The caps 10 and 25 are held in pressure contactwith (a part around) the anus 5 a and (a part around) the pubic region 5b, respectively, of the patient 5 by a supporter 6.

[0173] The supporter 6 has a circumferential belt 7 and a plurality ofstrings 8 a, 8 b and 8 c. The circumferential belt 7 is wound around thebody of the patient 5. Ends of the upper strings 8 a and 8 b areconnected to opposite sides of an upper part of the circumferential belt7. The lower strings 8 c is connected to the middle of a lower part ofthe circumferential belt 7. A flexible fitting ring 9 is held at threepoints by ends of the upper strings 8 a and 8 b and an end of the lowerstring 8 c. As shown in phantom lines in FIG. 24, the fitting ring 9 isdeformed into an elliptical shape elongated in a vertical direction andplaced in a position surrounding the anus 5 a and the pubic region 5 bof the patient 5.

[0174] The stool receiving cup 10 is placed over the anus 5 a of thepatient 5. The urine receiving cup 25 has a receiving port which isplaced over the pubic region 5 b of the patient 5. In this state, bothsides of the fitting ring 9 are hooked on hook pieces 9 a and 9 battached to both sides of the stool receiving cup 10 and the urinereceiving cup 25, respectively, as shown in solid lines in FIG. 24. Bythe supporter 6, the stool receiving cup 10 and the receiving port ofthe urine receiving cup 25 are held in pressure contact with (a partaround) the anus 5 a and (a part around) the pubic region 5 b,respectively, of the patient 5.

[0175] On both sides of the stool receiving cup 10, attachment sensorsS3 for detecting whether the stool receiving cup 10 and the urinereceiving cup 25 are properly attached are provided. Each of theattachment sensors S3 comprises a limit switch in this embodiment. Thesensors S3 have actuators which are slidably mounted on the upperstrings 8 a and 8 b. The sensors S3 are thereby turned on when thetension of the upper strings 8 a and 8 b becomes a predetermined valueor lower (improper attachment), and turned off when the tension becomesa predetermined value or higher.

[0176] To attach the stool receiving cup 10 and the urine receiving cup25 to a patient 5 in a sitting position, a cushion 34 a having a U-shapewith an opening at the front as shown in FIG. 25 is placed on thesitting surface of a chair 34. Namely, by seating the patient 5 on thecushion 34 a and placing a lower (rear) part of the stool receiving cup10 in the opening 34 b of the cushion 34 a, the stool receiving cup 10can be prevented from contacting the sitting surface of the chair 34.

[0177] The stool receiving cup 10 and the urine receiving cup 25 areconstituted as shown in FIG. 26 to FIG. 31. The stool receiving cup 10is formed in a cylindrical shape elongated in a longitudinal directionas a whole. Namely, the stool receiving cup 10 has a width which issmaller than the vertical length thereof and is elongated in thelongitudinal direction. The stool receiving cup 10 has a cylindricalshape with a length of about 112 mm, a height of about 50 mm, and awidth of about 40 mm. The stool receiving cup 10 is partitioned intofront and rear (right and left in FIG. 26) sections by a partition 11located at a longitudinal intermediate part therein. Namely, in thestool receiving cup 10, a stool chamber 12 and an auxiliary machinechamber 14 are formed on the front side and the rear side, respectively,of the partition 11. The front side (left side in FIG. 26) of the stoolchamber 12 opens to the outside (front) as a stool receiving port 12 a.A ring-shaped sealing member 13 of a soft rubber or resin is attached onthe edge of the receiving port 12 a so that the receiving port 12 a canbe in close contact with the part around the anus 5 a. The stool chamber12 and the auxiliary machine chamber 14 must be as water-tight aspossible.

[0178] The partition 11 is made of a hard plastic material with highstrength. A discharge pipe 16 extends in the longitudinal direction andis rotatably supported by the partition 11. The discharge pipe 16 has afront end exposed in the stool chamber 12. A first nozzle 15 (stoolpulverizer) for injecting washing water (washing liquid) is located inthe stool chamber 12 and attached to the front end of the discharge pipe16. The first nozzle 15 is set to inject the washing liquid in adirection perpendicular to the axis of the discharge pipe 16.

[0179] A motor (a ultrasonic motor in this embodiment) M is attached onthe side of the auxiliary chamber 14 of the partition 11. The motor M isused to rotate the discharge pipe 16. The motor M has a ring shape andthe discharge pipe 16 extends through the hollow of the motor M. Themotor M is rotatably driven by signals from a terminal circuit board 60housed in the auxiliary machine chamber 14. Namely, to pulverize stoolin the stool chamber 12, the first nozzle 15 is oriented downward andthe discharge pipe 16 is rotated forward and backward so that the firstnozzle 15 can be swung through an angle of 90° to the right and leftfrom a vertical line for a predetermined period of time (about 20seconds in this embodiment). When pulverizing of the stool is completed,the discharge pipe 16 is rotated in one direction for a predeterminedperiod of time (ten seconds in this embodiment) so that the first nozzlecan be rotated through 360° to wash the anus 5 a and the inside of thestool cup 10.

[0180] The discharge pipe 16 is rotatably connected to a supply pipe 18provided in the auxiliary machine chamber 14 via a rotary joint 17. Thesupply pipe 18 is connected to a hereinafter described washing watersupply unit 40 via a supply passage 20 a formed through a rear wall 20of the auxiliary machine chamber 14 and a supply passage 21 a formedthrough a rear joint 21. Water (warm water) supplied from the washingwater supply unit 40 is injected from the first nozzle 15 into the stoolchamber 12. The stool excreted in the stool chamber 12 is pulverized andthe anus 5 a of the patient 5 is washed by the washing water.

[0181] The first nozzle 15 injects washing water in a shape of a sectorhaving an angle α of about 110° and a width of about 1 mm. A stooldischarge pipe 23 is provided at a lower part in the auxiliary machinechamber 14. The stool discharge pipe 23 has a front end which isconnected to a lower rear part of the stool chamber 12 and opens in thestool chamber 12, and a rear end which is connected to a hereinafterdescribed stool discharge unit 45 via a stool discharge passage 20 bformed through the rear wall 20 of the auxiliary machine chamber 14 anda stool discharge passage 21 b formed through the rear joint 21. By thestool discharge unit 45, the stool pulverized in the stool chamber 12 issucked and removed (discharged) to the outside.

[0182] The urine receiving cup 25 has a receiving port which is open atthe front as shown in FIGS. 26 and 27. The urine receiving cup 25 isformed in a conical shape with an upper surface which inclined downwardtoward the rear. The urine receiving cup 25 has a length of about 52 mm,a height of about 55 mm, and a width of about 36 mm.

[0183] The urine receiving cup 25 has a receiving port 25 a having anelliptical shape elongated in a vertical direction at the front. Asealing member 26 of a soft rubber or resin is attached on the edge ofthe receiving port 25 a so that the receiving port 25 a can be in closecontact with the area around the pubic region 5 b. A urine dischargehose 27 is connected to a lower rear part of the urine receiving cup 25.The urine discharge hose 27 has a diameter of about 10 mm. The urinedischarge hose 27 has a rear end connected to an upper part of a urinedischarge passage 20 c formed through the rear wall 20 of the auxiliarychamber 14. Namely, the urine discharge hose 27 is connected to ahereinafter described urine discharge unit 50 via the urine dischargepassage 20 c and a urine discharge passage 21 c formed through the rearjoint 21. By the urine discharge unit 50, the urine excreted in theurine receiving cup 25 is sucked and removed to the outside.

[0184] To provide a function of washing the pubic region 5 b of thepatient 5, a second nozzle 28 is attached at a rear part in the urinereceiving cup 25. The second nozzle 28 is connected to a mid-portion ofthe supply pipe 18 via a second discharge hose 29, an electromagneticvalve 30 and a branch connection 31. By opening the electromagneticvalve 30 when the patient 5 finishes urinating, washing water (hotwater) supplied from the washing water supply unit 40 is injected to thepubic region 5 b of the patient 5 from the second nozzle 28. In thiscase, the washing water is injected from the second nozzle 28 at anangle of, for example, 40°.

[0185] As shown in FIG. 26 and FIG. 29, the stool discharge passages 20b and 21 b are faced to each other at the axis C of the rear joint 21.The supply passages 20 a and 21 a are faced to each other in a positionoffset from the axis C. The urine discharge passages 20 c and 21 c arefaced to each other in a position offset from the axis C. As shown inFIG. 7, the position where the supply passages 20 a and 21 a are facedto each other and the position where the urine discharge passages 20 cand 21 c are faced to each other are vertically symmetric with respectto the axis C. At the facing parts of the supply passage 21 a and theurine discharge passage 21 c in the rear joint 21, slots 21 a-1 and 21c-1 (which serve as connection passages) having a shape of a 120 degreearc about the axis C.

[0186] The rear joint 21 is connected to the rear wall 20 via acylindrical coupler 22. The rear joint 21 is rotatable through an angleof about 120° around its axis so that the rear joint 21 can be rotatedrelative to the rear wall 20 when the patient 5 rolls to the right orleft and the stool receiving cup 10 and the urine receiving cup 25 arerotated to the right or the left. Namely, the hoses of the washing watersupply device 40, the stool discharge unit 45 and the urine dischargeunit 50 can be prevented from being twisted.

[0187] A stool sensor S1 is attached on the outer periphery of the stoolchamber 12 (FIG. 26). A urine sensor S2 is attached on the outerperiphery of an upright portion of the urine discharge passage 20 c(FIG. 30). Detection signals from the stool sensor S1 and the urinesensor S2 (each of which corresponds to the sensor unit 400) aretransmitted to the terminal circuit board 60 described previously. Thestool sensor S1 and the urine sensor S2 are electrostatic capacitysensors of the same type.

[0188] The stool sensor S1 (the urine sensor S2) corresponds to thesensor unit 400 described previously. Thus, the outer peripheral wall ofthe stool chamber 12, namely the stool receiving cup 10 is made of aninsulating material such as a plastic. Ring-shaped transmissionelectrode 24 a (corresponding to 401), protection electrode 24 b(corresponding to 403), and a reception electrode 24 c (corresponding to402) are wound around the outer periphery of the stool chamber 12 atspecified longitudinal intervals. The transmission electrode 24 a,protection electrode 24 b and the reception electrode 24 c are connectedto a detecting circuit 24 d (which corresponds to the circuit except theelectrodes shown in FIG. 1).

[0189] The electrostatic capacity between the transmission electrode 24a and the reception electrode 24 c varies depending upon whether thereis stool between them. Thus, by detecting the variation of theelectrostatic capacity with the detecting circuit 24 d, it can bedetermined whether there exists stool in the stool receiving cup 10.

[0190] The washing water supply unit 40 is for supplying water or watermixed with an antiseptic or a liquid soap as washing liquid (washingwater). As shown in FIG. 26, the washing water supply unit 40 has a warmwater tank 41 for adjusting the washing water to a predeterminedtemperature. The warm water (washing water) in the warm water tank 41 issupplied to the stool receiving cup 10 through a warm water pump P1 anda supply hose 42. A high-temperature sensor S4 and a low-temperaturesensor S5 are provided in the warm water tank 41. The high-temperaturesensor S4 is turned on when the temperature becomes, for example, 42° C.or higher. The low-temperature sensor S5 is turned on when thetemperature becomes, for example, 25° C. or lower. When the sensor S4 orS5 is turned on, the warm water pump P1 is stopped. When the stoolsensor S1 or the urine sensor S2 is actuated when the sensors S4 and S5are off, the warm water pump P1 is activated and washing water isinjected from the first nozzle 15 or the second nozzle 28 (to wash theanus 5 a or the pubic region 5 b of the patient 5).

[0191] The stool discharge unit 45 described previously has a sealedstool tank 46 as shown in FIG. 26. An upper part of the stool tank 46 isdetachably connected to the stool discharge passage 21 b via a stooldischarge hose 47 (with a diameter of, for example, about 10 mm). Anupper part of the stool tank 46 is connected to (a suction port of) astool suction pump P2 via a suction hose 48. The stool suction pump P2has a discharge pipe to which a catalyst (deodorizer) 49 is connected.The stool suction pump P2 is activated when the stool sensor S1 isactuated and establishes a negative pressure within the stool tank 46 sothat stool having flown down to a lower part of the stool chamber 12 canbe sucked into the stool tank 46. Gas in the stool tank 46 sucked by thestool suction pump P2 is purified by the catalyst 49 and discharged intothe outside air. The stool tank 46 is provided with a fullness sensor S6for detecting the fullness of the stool tank 46.

[0192] The urine discharge unit 50 has a sealed urine tank 51 as shownin FIG. 26. An upper part of the urine tank 51 is connected to the urinedischarge passage 21 c via a urine discharge hose 52. An upper part ofthe urine tank 51 is connected to (a suction port of) of a urine suctionpump P3 via a suction hose 53. The urine suction pump P3 has a dischargepipe to which a catalyst (deodorizer) 54 is connected. The urine suctionpump P3 is activated when the urine sensor S2 is actuated andestablishes a negative pressure within the urine tank 51 so that urinehaving flown down to a lower part of the urine receiving cup 25 can besucked into the urine tank 51. Gas in the urine tank 51 sucked by theurine suction pump P3 is purified by the catalyst 54 and discharged intothe outside air. The urine tank 51 is provided a fullness sensor S7 fordetecting the fullness of the urine tank 51.

[0193] In FIG. 26, designated as 70 is an external controller forapplying a specified power source voltage to the terminal circuit board60 described previously. The controller 70 communicates with theterminal circuit board 60 through a communication line 64 to controleach equipment. FIG. 33 is a block diagram of the terminal circuit board60 and a control unit incorporated in the controller 70, FIG. 34 is aflowchart of the control unit. In FIG. 34, designated as 61 is anattachment control unit incorporated in the terminal circuit board 60,as 71 is an external control unit incorporated in the controller 70. Theattachment control unit 61 has a terminal microcomputer 62. Data fromthe stool sensor S1 and the urine sensor S2 are inputted into theterminal microcomputer 62 via detecting circuits 24 and 24′,respectively. A signal from the attachment sensor S3 is also inputtedinto the terminal microcomputer 62. Further, data from an origin sensorS8 for detecting the original position of the first nozzle 15 are alsoinputted into the microcomputer 62 via an origin circuit 63. Themicrocomputer 62 transmits the data and signal to the external controlunit 71 of the controller 70 via the communication circuit 64, andreceives data processed in the external control unit 71 to control themotor M via a motor driving circuit 65. Designated as 66 is a powersource circuit for supplying power from the controller 70 side to theterminal circuit board 60.

[0194] The external control unit 71 of the controller 70 has a hostmicrocomputer 72, into which the data and signal from the terminalmicrocomputer 62 are inputted via communication circuit 73. Signals fromthe high-temperature sensor S4, the low-temperature sensor S5, thefullness sensors S6 and S7, a manual stool switch SW1, a manual urineswitch SW2 and so on are also inputted into the microcomputer 72.Further, the driving time and the forward and reverse rotation angles ofthe motor M, set values of the sensors and so on are inputted into themicrocomputer 72 through operation buttons 74. The host microcomputer 72stores and arithmetically processes the inputted data and signals andoutputs specified command signals to the terminal microcomputer 62, andcontrols the warm water pump P1, the stool suction pump P2 and the urinesuction pump P3 via driving circuits. In abnormal situations, themicrocomputer 72 actuates an alarm 75 or displays a necessary indicationon a liquid crystal display 76. When necessary, the data in thecontroller 70 are transmitted to a personal computer 78 installed in acentral control room via a communication line and stored and centrallymanaged therein. Designated as 77 is a power source circuit of thecontroller 70.

[0195] The operation of the attachment control unit 61 and the externalcontrol unit 71 will be described with reference to the flowchart inFIG. 34. In FIG. 34, T1 to T21 represents the steps of the flowchart.When the control program is stared in step T1, signals from theattachment sensor S3, the high-temperature sensor S4, thelow-temperature sensor S5, the fullness sensor S6 of the stool tank 46and the fullness sensor S7 of the urine tank 51 are inputted in step T2.In step T3, it is determined whether there is an abnormality in eachsensor. When an abnormality is found in step T3, the program goes tostep T16 to display an error message and set off an alarm. When there isno abnormality (the signals are off), the program goes to step T4. Instep T4, it is determined whether the device is in automatic operationor not.

[0196] In the case of automatic operation, it is determined whether thestool sensor S1 is on or not in step T5. When the stool sensor S1 is on,the program performs steps T7 to T10 to activate the warm water pump P1and the stool suction pump P2 and rotates the motor M forward andreverse for about 20 seconds. Then, warm water is injected from thefirst nozzle 15 and the first nozzle 15 is swung through about 90° tothe right and left from a vertical line. Stool 5 c accumulated at thebottom of the stool receiving cup 10 is thereby pulverized. The thuspulverized stool 5 c is sucked and discharged through the stooldischarge pipe 23, the stool discharge passages 20 b and 21 b and thestool discharge hose 47 and received in the stool tank 46.

[0197] After having been rotated in forward and reverse for 20 seconds,the motor M is rotated in one direction for about 10 seconds in stepsT11 and T12. Then, the first nozzle 15 injects washing water via thedischarge pipe 16 while being rotated about a longitudinal line to washthe entire inside of the stool receiving cup 10 and the anus 5 a of thepatient 5. Then, the program performs steps T13 to T15 to stop the warmwater pump 13, the motor M, and the stool suction pump P2, and thenjumps to step T2.

[0198] When the stool sensor S1 is off in step T5, it is determinedwhether the urine sensor S2 is on in step T6. When the urine sensor S2is off, the program jumps to step T2. When the urine sensor S2 is on,the program performs steps T19 to T21 to activate the urine suction pumpP2 for 30 seconds. The urine excreted into the urine cup 25 is therebysucked and received in the urine tank 51. After stopping the urinesuction pump P2 in step T21, the program jumps to step T2.

[0199] When the device is not in automatic operation, namely, in manualoperation, in step T4, it is determined whether the manual stool switchSW1 is on in step T17. When the manual stool switch SW1 is on, theprogram performs steps T7 to T15 whereas when the manual stool switchSW1 is off, the program goes to step T18. In step T18, it is determinedwhether the manual urine switch SW2 is on. When the manual urine switchSW2 is on, the program performs steps T19 to T21 whereas when the manualurine switch SW2 is off, the program jumps to step T2. When the pubicregion 5 b of the patient 5 is washed after urination, theelectromagnetic valve 30 shown in FIG. 4 is opened and the warm waterpump P1 is activated before the urine suction pump P3 is stopped in stepT21 so that the washing water can be injected from the second nozzle 28to the pubic region 5 b of the patient 5.

[0200] Description of FIG. 35 and FIG. 36

[0201]FIG. 35 and FIG. 36 show another example in which acapacitance-coupled sensor is provided in an excrement cup. In thisexample, the sensor unit 400B as shown in FIG. 6 or the sensor unit 400Cas shown in FIG. 9 is provided in the excrement cup. In FIG. 35 and FIG.36, a sensor unit corresponding to the sensor unit 400B or 400C isreferred to as “net” and designated as 171.

[0202] An excrement disposal device A-3 has a stool receiving cup 160and a urine receiving cup 113 which are formed of a plastic materialseparately. As shown in FIG. 35, the stool receiving cup 160 ispartitioned into front and rear sections by a partition 160 b. Namely,in the stool receiving cup 126, a stool chamber 160 c for receivingstool and an auxiliary machine chamber 160 d for housing auxiliarymachines are formed at the front and rear, respectively. The stoolchamber 160 c has a lower part which is tapered downward like a funnelwith a discharge port 161 at the bottom. The discharge port 161 iscommunicated from the lower rear end of the stool receiving cup 160 tothe outside via a stool discharge passage 162 formed at the bottom ofthe stool receiving cup 160. A multiplicity of projections 163 areformed over almost the entire inner surfaces of the stool chamber 160 cto prevent adhesion of stool.

[0203] A stool pulverizer 170 is provided in the stool chamber 160 c.Namely, a net (net member) 171 with a specified mesh size (5 mm in thisembodiment) is strung across a lower part in the auxiliary machinechamber 160 d (the sensor unit 400C as shown in FIG. 9 or the sensorunit 400B as shown in FIG. 6 may be used). The net 171 is placed overthe discharge port 161. Namely, the net 171 is placed between the stoolreceiving port and the discharge port 161 so that stool excreted intothe stool receiving cup 160 cannot move down into the discharge port 161without passing through the net 171. A first nozzle 173 for injectingwashing water (water or warm water) W is provided at an upper part inthe stool chamber 160 c. A discharge pipe 175 extends through thepartition 160 b and rotatably supported thereby. The discharge pipe 175has a front end to which the first nozzle 173 is attached. The dischargepipe 175 is rotatably connected to a first introduction pipe 177 via apipe joint 176. The first introduction pipe 177 is connected to awashing water supply unit via a relay 178.

[0204] The first nozzle 173 injects washing water to the upper surfaceof the net 171. Part of the washing water is also injected to the anus 5a of the patient 5. Namely, the washing water is injected into a shapewhich is so board in the longitudinal direction as to extend from a rearpart of the net 171 to the anus 5 a of the patient 5 as shown in FIG.36, and narrow (linear) in the lateral direction as shown in FIG. 35.

[0205] The first nozzle 173 is swung to the right and left via thedischarge pipe 175 by a nozzle driving unit 180 housed in the auxiliarymachine chamber 160 d. As shown in FIG. 35, the nozzle driving unit 180has an electric motor (driving unit) 184 having an output shaft 185 towhich a connecting rod 190 is connected via a crank web 189. Theconnecting rod 190 has an end connected to a rack 191 slidably attachedto a rack holder 192. The rack 191 is in meshing engagement with apinion gear 193 attached to a rear part of the discharge pipe 175.

[0206] The rotation of the electric motor 184 is converted into linearreciprocating motion by the crank web 189 and the connecting rod 190,and the rack 191 is reciprocated up and down. Namely, by thereciprocating motion of the rack 191, the first nozzle 173 is swung tothe right and left through a specified angle via the pinion gear 193 andthe discharge pipe 175. The washing water W injected from the firstnozzle 173 is moved to the right and left as shown in FIG. 35 topulverize stool (shits) 5 d on the net 171. The pulverized stool flowsdown to the discharge port 161 through the net 171.

[0207] The stool discharge passage 162 is connected to a stool dischargeunit, by which the stool pulverized by the stool pulverizer 170, urinehaving flown down from the urine receiving cup 113 into the stoolchamber 160 c, water injected from the first and second nozzles 173 and115 and used and so on are sucked through the stool discharge passage162 and discharged to the outside.

[0208] Description of FIG. 37 to FIG. 39

[0209]FIG. 37 to FIG. 39 show an example of an arrangement of a urinedischarge hose and a rotary joint which is suitable when a stoolreceiving cup and a urine receiving cup are formed as separate piecesdetachable from each other. A stool receiving cup 10 and a urinereceiving cup 25 as shown in FIG. 26 are used. In this example, therotary joint 320 is provided outside and in the vicinity of the stoolreceiving cup 10. The rotary joint 320 has the same function as thejoint 21 shown in FIG. 26 but different from it in that it is locatedoutside the stool receiving cup 10. Namely, the rotary joint 320 has afirst member 321, a second member 322 rotatably connected to the firstmember 321, and a coupler 323 for connecting hoses and so on to thesecond member 322. The rotary joint 320 is connected to a mid-portion ofa stool discharge hose 47 and a washing liquid supplying hose 42 for thestool receiving cup in the vicinity of the stool receiving cup 10. Thus,the rotary joint 320 can be externally attached to the stool receivingcup 10, and twist of hoses 47 and 42 can be prevented from affecting thewearer.

[0210] A urine discharge hose 330 (corresponding to the urine dischargehose 27 in FIG. 26) extending from the urine receiving cup 25 isconnected to a urine tank via the rotary joint 320. The part of theurine discharge hose 330 between the urine receiving cup 25 and therotary joint 320 is sufficiently long. Namely, the urine discharge hose330 extends backward almost horizontally from the urine receiving cup 25and is then curved upward. Then, the urine discharge hose 330 is curvedtoward the front and then toward the rear, and finally connected to therotary joint 320. The urine discharge hose 330 has a loop portion 330 aconstituted of the above curved portions and curved through almost 270°.Because of the loop portion 330 a, urine tends to collect in the part ofthe urine discharge hose 330 between the urine receiving cup 25 and therotary joint 320 (trap effect of the loop portion 330 a). A urine sensorS2 is attached to the part where urine tends to collect.

[0211] By forming the loop portion 330 a, the urine discharge hose 330has a part which crosses over itself at an angle of about 90°. A holdingclip 340 is provided at the crossover point. The holding clip 340 hastwo hose holding part 340 a and 340 b. The holding part 340 a and 340 bare holes extending perpendicular to each other as shown in FIG. 38 andFIG. 39. The urine discharge hose 330 is slidably inserted through thehose holding parts 340 a and 340 b. The holding clip 340 may be made ofa synthetic resin, for example.

[0212] By changing the positions of the parts of urine discharge hose330 extending through the holding clip 340, the position of the urinereceiving cup 25 relative to the stool receiving cup 10 can be adjusted.Namely, by changing the position of the part of the urine discharge hose330 extending almost horizontally with respect to the holding clip 340,the longitudinal position of the urine receiving cup 25 can be adjusted.Also, by changing the position of the part of the urine discharge hose330 extending almost vertically with respect to the holding clip 340,the vertical position of the urine receiving cup 25 can be adjusted.

[0213] Although description has been made of the embodiments of thisinvention, it should be understood that this invention is not limited tothe embodiments but can be modified in various ways. For example, thesensor units (400, 400B, 400C) can be used in various applications suchas detection of the presence or absence or the amount of a substance ina piping system. The high-frequency oscillation circuit 410 and thedetection circuit 420 are not limited to the ones shown in theembodiments but may be any known circuits. It should be understood thatthe object of this invention is to provide not only devices and methodsspecifically described but also devices and a methods substantiallydescribed as preferred and advantageous embodiments.

1. A capacitance-coupled sensor comprising: a sensor unit having atransmission electrode, a reception electrode capacitively couplable tosaid transmission electrode, and a shielding electrode interposedbetween said transmission electrode and said reception electrode forshielding the transmission electrode and the reception electrode fromeach other, a high-frequency oscillator interposed between saidtransmission electrode and said shielding electrode for applying ahigh-frequency voltage to said transmission electrode; and a detectorinterposed between said reception electrode and said shielding electrodefor converting a high-frequency voltage outputted from said receptionelectrode into a DC voltage.
 2. The capacitance-coupled sensor asclaimed in claim 1, configured to detect the presence or absence of asubstance.
 3. The capacitance-coupled sensor as claimed in claim 2,further comprising a comparator for comparing an output voltage fromsaid detector with a specified threshold voltage and outputting thecomparison result.
 4. The capacitance-coupled sensor as claimed in claim2, further comprising an insulating wall member having an inner surfacewith which a substance comes into contact, wherein said sensor unit isprovided on an outer surface of or in said wall member.
 5. Thecapacitance-coupled sensor as claimed in claim 4, wherein said wallmember serves as a wall member of a vessel or a piping system.
 6. Thecapacitance-coupled sensor as claimed in claim 2, wherein said sensorunit is constituted of at least three conductive wires extending inparallel to each other at small intervals as a whole.
 7. Thecapacitance-coupled sensor as claimed in claim 6, wherein said pluralityof conductive wires are divided into first to third groups each having aplurality of conductive wires, a plurality of conductive wires in saidfirst group serving as a plurality of transmission electrodes, aplurality of conductive wires in said second group serving as aplurality of reception electrodes, and a plurality of conductive wiresin said third group serving as a plurality of shielding electrodes, saidconductive wires serving as shielding electrodes being arranged betweeneach of conductive wires serving as transmission electrodes and each ofsaid conductive wires serving as reception electrodes, said conductivewires serving as transmission electrodes being electrically connectedwith each other at one end, said conductive wires serving as saidreception electrodes being electrically connected with each other at oneend, and said conductive wires serving as shielding electrodes beingelectrically connected with each other at one end.
 8. Thecapacitance-coupled sensor as claimed in claim 7, wherein each of saidconductive wires is coated with an insulating coating material.
 9. Thecapacitance-coupled sensor as claimed in claim 7, further comprisingspacer members provided at both longitudinal ends of said conductivewires for maintaining the intervals between said conductive wires. 10.The capacitance-coupled sensor as claimed in claim 2, wherein each ofsaid transmission electrode, said reception electrode and said shieldingelectrode is constituted of a plurality of conductive wires, saidplurality of conductive wires constituting said transmission electrodeextending in parallel to each other at specified intervals on a firstplane, said plurality of conductive wires constituting said receptionelectrode being located on a second plane generally parallel to saidfirst plane and extending in a direction crossing the conductive wiresconstituting said transmission electrode at small intervals, saidplurality of conductive wires constituting said shielding electrodebeing located between said first and second planes and extending in adirection crossing said plurality of conducive wires constituting saidtransmission electrode and said plurality of conducive wiresconstituting said reception electrode, whereby said conductive wiresconstituting said transmission electrode, said conductive wiresconstituting said reception electrode, and said conductive wiresconstituting said shielding electrode are mutually crossed at amultiplicity of points as seen in a direction perpendicular to saidfirst plane so that the sensor unit can be in the form of a sheet with amultiplicity of mesh apertures as a whole.
 11. The capacitance-coupledsensor as claimed in claim 10, wherein said conductive wiresconstituting said transmission electrode are electrically connected toeach other at one end, wherein said conductive wires constituting saidreception electrode are electrically connected to each other at one end,and wherein said conductive wires constituting said shielding electrodeare electrically connected to each other at one end.
 12. Thecapacitance-coupled sensor as claimed in claim 10, wherein, when saidplurality of conductive wires constituting said transmission electrode,said plurality of conductive wires constituting said reception electrodeand said plurality of conductive wires constituting said shieldingelectrode are represented as first to third conductive wire groups,respectively, two of said first to third conductive wire groups extendperpendicular to each other and the other conductive wire group extendsat an angle of about 45° to said two conductive wire groups.
 13. Thecapacitance-coupled sensor as claimed in claim 10, wherein each of saidconductive wires is coated with an insulating coating material.
 14. Thecapacitance-coupled sensor as claimed in claim 10, further comprisingspacer members provided at both longitudinal ends of said conductivewires for maintaining the intervals between said conductive wires. 15.The capacitance-coupled sensor as claimed in claim 14, wherein saidspacer members are arranged in the form of a ring with a large openingin the center, and wherein said conductive wires extend across saidopening of said spacer members with their longitudinal ends fixed tosaid spacer members.
 16. The capacitance-coupled sensor as claimed inclaim 1, configured to detect the amount of a substance.
 17. Thecapacitance-coupled sensor as claimed in claim 16, further comprising avessel for containing a substance, wherein said sensor unit is elongatedin the direction in which the level of said substance in said vesselchanges, and wherein at least the part of said vessel where said sensorunit is located and around it have insulation.
 18. Thecapacitance-coupled sensor as claimed in claim 17, wherein said sensorunit is provided on an outer surface of or in a wall of said vessel. 19.The capacitance-coupled sensor as claimed in claim 17, wherein saidsensor unit is located outside and in the vicinity of said vessel. 20.The capacitance-coupled sensor as claimed in claim 1, wherein aplurality of sensor units are provided, wherein transmission electrodesof said sensor units are connected in parallel to said high-frequencyoscillator, wherein reception electrodes of said sensor units areconnected in parallel to said detector, and a selection unit forselectively connecting one of said transmission electrode to saidhigh-frequency oscillator is provided.
 21. The capacitance-coupledsensor as claimed in claim 1, wherein a plurality of sensor units areprovided, wherein transmission electrodes of said sensor units areconnected in parallel to said high-frequency oscillator, whereinreception electrodes of said sensor units are connected in parallel tosaid detector, and wherein a selection unit for selectively connectingone of said reception electrode to said detector is provided.
 22. Thecapacitance-coupled sensor as claimed in claim 1, wherein saidtransmission electrode, said reception electrode and said shieldingelectrode are supported by a support of an insulating synthetic resin.23. The capacitance-coupled sensor as claimed in claim 22, wherein saidtransmission electrode, said reception electrode and said shieldingelectrode are so thin as to be able to be bent easily, and wherein saidsupport is flexible so that it can be bent easily together with saidtransmission electrode, said reception electrode and said shieldingelectrode.
 24. The capacitance-coupled sensor as claimed in claim 23,wherein said transmission electrode, said reception electrode and saidshielding electrode are embedded in said support, and wherein conductivewires extending from said transmission electrode, reception electrodeand shielding electrodes extend out of said support.
 25. Thecapacitance-coupled sensor as claimed in claim 1, wherein saidhigh-frequency oscillator is a clock incorporated in a computer.
 26. Thecapacitance-coupled sensor as claimed in claim 2 wherein said substanceis a living body, excrement of a living body, gas, liquid, solid matter,powder, particulate matter or gelatinous substance.
 27. Thecapacitance-coupled sensor as claimed in claim 6 further comprising anexcrement cup attachable to a patient for receiving excrement of saidpatient, wherein said sensor unit is provide on an outer surface of saidexcrement cup or an outer surface of an excrement discharge passageextending from said excrement cup.
 28. The capacitance-coupled sensor asclaimed in claim 6 further comprising an excrement cup attachable to apatient for receiving at least excrement of said patient, and a stooldischarge passage for discharging at least stool from said excrement cupwith an in-cup opening which opens upward in said excrement cup, whereinsaid sensor unit is placed across said in-cup opening so that stoolexcreted by said patient can be received by the sensor unit, and saidstool on said sensor unit is passed through said sensor unit when saidstool discharge passage is subjected to suction.
 29. A method fordetecting a substance using a capacitance-coupled sensor comprising asensor unit having a transmission electrode, a reception electrodecapacitively couplable to said transmission electrode, and a shieldingelectrode interposed between said transmission electrode and saidreception electrode for shielding said transmission electrode and saidreception electrode from each other, comprising the steps of: applying ahigh-frequency voltage across said transmission electrode and saidreception electrode, converting a high-frequency voltage outputted fromsaid reception electrode into a DC voltage, and detecting at leasteither of the presence or absence or the amount of said substance basedon the magnitude of said DC voltage.